[PATCH] D131479: Handle explicitly defaulted consteval special members.

[Aaron Ballman via Phabricator via cfe-commits]

aaron.ballman added a comment.

In D131479#3753462 <https://reviews.llvm.org/D131479#3753462>, @Mordante wrote:

> This change breaks the libc++ test `libcxx/test/std/utilities/optional/optional.object/optional.object.ctor/move.fail.cpp`. (https://buildkite.com/llvm-project/libcxx-ci/builds/13149#0182d0d4-341a-4b41-b67f-12937f41e6d5)
>
> Looking at the description of this patch it should only affect `consteval` functions, but it seems to affect `constexpr` functions too. Can you have a look?

Agreed that we should take a look, but it's interesting to note that libstdc++ seems to have a different behavior than libc++ here: https://godbolt.org/z/6cWhf6GYj (the last three compiler panes show Clang 14 libstd++, Clang 14 libc++, and Clang trunk libc++). How sure are you that the libc++ test is actually correct, because (without checking the standard, so take with a giant grain of salt) this seems like it might have fixed a bug in libc++? The release note says this is expected to impact constexpr and consteval default special member functions, so behavioral changes to `constexpr` aren't unexpected (though I agree that the commit message didn't mention `constexpr` so the changes may seem surprising).


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https://reviews.llvm.org/D131479